Hi wooliewillie,
In addition to what Mac suggests ...

Successively click on "Opt | Preferences | MIDI Driver", and the above screen will pop up.
Set those settings shown by numerals 1 and 2. If your computer is a 64-bit system, you will not be able to use the VSC/DXi shown by #3 (this only works on a 32-bit system). If your system is 64-bit, for the 3rd selection choose "Coyote WT" from the dropdown menu.
BIAB requires a softsynth to be active for rendering to work. It is worth checking to see that this is correctly in place on your machine.
Hope this helps,
Noel